Delayed LDV-induced polioencephalomyelitis after treatment with an anti-LDV IgG2a switch variant. Onset of paralysis was monitored daily in groups of five or six immunosuppressed C58 mice infected with LDV and treated on days 2, 4, and 7 p.i. with NaCl alone or with anti-LDV switch variant-containing ascitic fluids diluted in NaCl to obtain similar antibody concentrations (IgG1, 1/10; IgG2a, 1/1; IgG2b, 1/10; IgG3, 1/5).